阅读说明：本技术 一种纳米导电材料/聚合物复合气敏传感器及其制备方法 (Nano conductive material/polymer composite gas sensor and preparation method thereof ) 是由 汪桢 李尤 罗斌 于 2018-11-22 设计创作，主要内容包括：本发明提供了一种导电纳米材料/聚合物复合气敏传感器及其制备方法,涉及气体传感器领域,其技术方案要点是包括基底以及设置在基底上的导电颗粒和聚合物基体,所述导电颗粒为纳米导电颗粒,所述聚合物处于拉伸状态,所述拉伸处于弹性形变范围内,其优点是拉伸状态下的聚合物基体受VOC蒸汽而迅速溶胀,从而使纳米导电颗粒粒子之间形成的导电网络迅速断开,以达到快速响应的目的,提高导电纳米材料/聚合物复合气敏传感器对VOC气体检测的灵敏度。(The invention provides a conductive nano material/polymer composite gas-sensitive sensor and a preparation method thereof, which relate to the field of gas sensors.)

1. A conductive nano material/polymer composite gas sensor is characterized in that: the conductive particle is a nano conductive particle, the polymer is in a stretching state, and the stretching is in an elastic deformation range.

2. The conductive nano material/polymer composite gas sensor as claimed in claim 1, whereinCharacterized in that: the conductive particles have a size of 10-200 nm and a specific surface area of 50m²/g-3000m²(ii)/g, density is 50g/L-200 g/L; the strain range of the polymer in a stretched state is 1% to 200%.

3. A preparation method of a conductive nano material/polymer composite gas sensor is characterized by comprising the following steps: the method for preparing the conductive nano material/polymer composite gas sensor of claim 1 or claim 2, comprising the following steps:

(a) dispersing the conductive particles in a solvent A, and uniformly dispersing by using ultrasonic waves to obtain a dispersion liquid a with the mass fraction concentration of α;

(b) dissolving the polymer in a stretched state in a solvent B, and uniformly dispersing by using ultrasonic waves to obtain a solution B with a mass fraction concentration of β;

(c) mixing the dispersion liquid a and the solution b in proportion, and uniformly dispersing by using ultrasound to obtain a mixed liquid c;

(d) adding an additive gamma into the mixed solution c, and uniformly dispersing by using ultrasonic waves to obtain a mixed solution d;

(e) preparing a layer of nano conductive particle/polymer composite film on the substrate by using a rotary coating method or a dip-coating method to prepare the composite gas sensor;

(f) placing the prepared composite gas-sensitive sensor in a vacuum oven at the temperature of f for vacuum drying;

(g) carrying out temperature stability treatment on the prepared composite gas sensor;

(h) carrying out steam stability treatment on the prepared composite gas sensor;

(i) and carrying out aging treatment on the prepared composite gas sensor.

4. The method for preparing the conductive nano material/polymer composite gas sensor according to claim 3, wherein the method comprises the following steps: the solvent a in the preparation method step (a) and the solvent B in the preparation method step (B) each include water, methanol, ethanol, isopropanol, glycerol, ethylene glycol, hexafluoroisopropanol, 1-dichloroethane, 1, 2-dichloroethane, acetone, butanone, hexafluoroacetone, N-octane, N-hexane, N-dodecane, N-dodecanethiol, toluene, benzene, ethylbenzene, o-xylene, p-xylene, m-xylene, dichloromethane, chloroform, N-dimethylformamide, N-dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone, tetrahydrofuran, cyclohexane, imidazole, or N-methylimidazole;

the α is 0.1-15%, the ultrasonic dispersion time is 10-120 min, and the ultrasonic dispersion power is 50-500 w.

5. The method for preparing the conductive nano material/polymer composite gas sensor according to claim 3, wherein the method comprises the following steps: the polymer in step (b) of the preparation method comprises polyvinyl alcohol, polyethylene glycol, polydimethylsiloxane, polycaprolactone, polyepichlorohydrin, an ethylene-vinyl acetate copolymer, poly (4-methylstyrene), polyisobutylene, polycarbonate, poly (4-methylstyrene), poly (carbomer ketone), a polystyrene-polyisoprene-polystyrene graft polymer, cellulose acetate, polymethyl methacrylate, poly (styrene-co-butadiene), polyvinyl stearate, hydroxypropyl cellulose, poly (butadiene), polyvinyl alcohol-vinyl acetate, ethyl cellulose, poly (vinyl acetate), polyethylene or polystyrene;

the β is 0.1-40%, the ultrasonic dissolving time is 1-60 min, and the ultrasonic dissolving power is 20-100 w.

6. The method for preparing the conductive nano material/polymer composite gas sensor according to claim 3, wherein the method comprises the following steps: the volume ratio of the dispersion liquid a to the solution b in the step (c) of the preparation method is 1:100-100:1, the ultrasonic dispersion time is 10min-120min, and the ultrasonic dispersion power is 50w-500 w.

7. The method for preparing the conductive nano material/polymer composite gas sensor according to claim 3, wherein the method comprises the following steps:

the gamma in the step (d) of the preparation method comprises one or more of tetrabutyl titanate, gamma-aminopropyl triethoxysilane, dicumyl peroxide, 4-hydroxybenzophenone laurate or benzophenone.

8. The method for preparing the conductive nano material/polymer composite gas sensor according to claim 3, wherein the method comprises the following steps: the substrate in the step (e) of the preparation method comprises a PCB substrate, a monocrystalline silicon substrate, a nylon plate substrate or a cotton fiber substrate, and gold interdigital electrodes are arranged on the substrate.

9. The method for preparing the conductive nano material/polymer composite gas sensor according to claim 2, wherein; in the step (f), the temperature f is 40-150 ℃, and the drying time is 3-48 h.

10. The method for preparing the conductive nano material/polymer composite gas sensor according to claim 3, wherein the method comprises the following steps:

the temperature stability treatment in the step (g) of the preparation method is that the materials are alternately placed at high temperature/low temperature for 3-100 times, each time the materials are placed for 10-1440 min, the high temperature is 50-150 ℃, and the low temperature is-20-30 ℃;

the steam stability treatment in the step (h) of the preparation method is that the raw materials are alternately placed for 3-100 times in a high-concentration/low-concentration VOC steam environment, each time the raw materials are placed for 10-1440 min, the high concentration of the VOC steam is 1000-100000 ppm, and the low concentration of the VOC steam is 0-100 ppm;

the aging treatment in the step (i) of the preparation method is natural aging in air, the air temperature is 20-30 ℃, and the aging time is 1day-7 day.

Technical Field

The invention relates to the field of gas sensors, in particular to a conductive nano material/polymer composite gas sensor and a preparation method thereof.

Background

With the new internet technology and internet of things, research and development of a high-portability micro-VOC gas sensor is a research hotspot at home and abroad at present, the future development trend of loading the VOC gas sensor on mobile-end electronic equipment such as mobile phones, tablet computers, wireless detection equipment and the like becomes, the emerging industry demands put more rigorous requirements on the low-power consumption performance of the VOC gas sensor, and the traditional metal oxide such as SnO₂、ZnO、Fe₂O₃High sensitivity and low costHowever, it is required to use it at a high temperature (200 ℃ C. -500 ℃ C.).

The polymer-based conductive composite material is a novel gas-sensitive functional material, and has the advantages of low price, simple forming process, good selectivity, good stability, usability at room temperature and the like, the polymer-based conductive composite material comprises an intrinsic type and a filling type composite material, the intrinsic type conductive composite material takes polyaniline, polypyrrole, polythiophene and other intrinsic conductive polymers as a matrix, a p-type semiconductor is formed by chemical or electrochemical doping, and has high sensitivity to a composite gas with redox characteristics, the filling type conductive composite material is formed by compounding an extrinsic conductive polymer matrix and a certain amount of conductive fillers such as carbon black, metal, carbon fiber, graphite and the like through solution or melt blending, the polymer absorbs the composite gas and swells to increase the distance between the conductive fillers, and the conductivity is reduced, wherein the nano carbon black has large specific surface area, good conductivity, good stability and the like, The price is low, and the nano carbon black/polymer-based conductive composite material is easy to process and produce in a large scale.

At present, the percolation threshold of carbon black can be greatly reduced by means of in-situ polymerization filling, emulsion blending filling, grafting modification and the like, and the sensitivity, stability and repeatability of the carbon black are improved, but most of researches are usually focused on saturated steam atmosphere or high steam partial pressure atmosphere, because the PVC (positive steam coefficient, namely, the system resistance is reduced along with the increase of steam concentration) effect rule of the conductive nano material/polymer-based conductive composite material is often in an exponential relationship, and steam molecules follow the gas adsorption rule in the low-concentration steam range (1-5% of saturated steam pressure), the response time of the conductive nano material/polymer-based conductive composite material is long, the resistance change is small, and the application range of the composite sensor is greatly limited.

As described above, how to improve the sensitivity of the conductive nanomaterial/polymer-based conductive composite material to VOC gas detection and reduce the response time on the premise of sensor stability, selectivity and room temperature testability is an urgent problem to be solved.

Disclosure of Invention

In order to solve the technical problems, the invention discloses a conductive nano material/polymer composite gas sensor and a preparation method thereof, and the technical scheme of the invention is implemented as follows:

a conductive nano material/polymer composite gas sensor comprises a substrate, conductive particles and a polymer matrix, wherein the conductive particles and the polymer matrix are arranged on the substrate, the conductive particles are nano conductive particles, the polymer is in a stretching state, and the stretching state is in an elastic deformation range.

Preferably, the conductive particles have a size of 10nm to 200nm and a specific surface area of 50m²G-3000m2/g, density 50g/L-200 g/L; the strain range of the polymer in a stretched state is 1% to 200%.

The invention also discloses a preparation method of the conductive nano material/polymer composite gas sensor, which is used for preparing the conductive nano material/polymer composite gas sensor and comprises the following steps of (a) dispersing the conductive particles in a solvent A to obtain a dispersion liquid a with the mass fraction concentration of α through ultrasonic uniform dispersion, (B) dissolving the polymer in a stretching state in a solvent B to obtain a solution B with the mass fraction concentration of β through ultrasonic uniform dispersion, (c) mixing the dispersion liquid a and the solution B according to a proportion to obtain a mixed liquid c through ultrasonic uniform dispersion, (d) adding an additive gamma into the mixed liquid c to obtain a mixed liquid d through ultrasonic uniform dispersion, (e) preparing a layer of nano conductive particle/polymer composite film on a substrate by using a rotary coating method or a dipping and pulling method to obtain a composite gas sensor, (f) placing the prepared composite gas sensor in a vacuum oven at f temperature for vacuum drying, (g) carrying out temperature stability treatment on the prepared composite gas sensor, (h) carrying out steam stability treatment on the prepared composite gas sensor to obtain the composite gas sensor.

The solvent A in the step (a) of the preparation method and the solvent B in the step (B) of the preparation method both comprise water, methanol, ethanol, isopropanol, glycerol, ethylene glycol, hexafluoroisopropanol, 1-dichloroethane, 1, 2-dichloroethane, acetone, butanone, hexafluoroacetone, N-octane, N-hexane, N-dodecane, N-dodecanethiol, toluene, benzene, ethylbenzene, o-xylene, p-xylene, m-xylene, dichloromethane, chloroform, N-dimethylformamide, N-dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone, tetrahydrofuran, cyclohexane, imidazole or N-methylimidazole, wherein α is 0.1-15%, the ultrasonic dispersion time is 10-120 min, and the ultrasonic dispersion power is 50-500 w.

The polymer in the step (b) of the preparation method comprises polyvinyl alcohol, polyethylene glycol, polydimethylsiloxane, polycaprolactone, polyepichlorohydrin, an ethylene-vinyl acetate copolymer, poly (4-methylstyrene), polyisobutylene, polycarbonate, poly (4-methylstyrene), poly (carbopol ketone), a polystyrene-polyisoprene-polystyrene graft polymer, cellulose acetate, polymethyl methacrylate, poly (styrene-co-butadiene), polyvinyl stearate, hydroxypropyl cellulose, poly (butadiene), polyvinyl alcohol-vinyl acetate, ethyl cellulose, poly (vinyl acetate), polyethylene or polystyrene, wherein β is 0.1-40%, the ultrasonic dissolving time is 1-60 min, and the ultrasonic dissolving power is 20-100 w.

The volume ratio of the dispersion liquid a to the solution b in the step (c) of the preparation method is 1:100-100:1, the ultrasonic dispersion time is 10min-120min, and the ultrasonic dispersion power is 50w-500 w.

The gamma in the step (d) of the preparation method comprises one or more of tetrabutyl titanate, gamma-aminopropyl triethoxysilane, dicumyl peroxide, 4-hydroxybenzophenone laurate or benzophenone.

The substrate in the step (e) of the preparation method comprises a PCB substrate, a monocrystalline silicon substrate, a nylon plate substrate or a cotton fiber substrate, and gold interdigital electrodes are arranged on the substrate.

In the step (f), the temperature f is 40-150 ℃, and the drying time is 3-48 h.

The temperature stability treatment in the step (g) of the preparation method is that the materials are alternately placed at high temperature/low temperature for 3-100 times, each time the materials are placed for 10-1440 min, the high temperature is 50-150 ℃, and the low temperature is-20-30 ℃; in the preparation method, in the step (h), the steam stability treatment is that the composite steam is alternately placed for 3-100 times in a high-concentration/low-concentration composite steam environment, each time is placed for 10min-1440min, the high concentration of the composite steam is 1000ppm-100000ppm, and the low concentration of the composite steam is 0ppm-100 ppm; the aging treatment in the step (i) of the preparation method is natural aging in air, the air temperature is 20-30 ℃, and the aging time is 1day-7 day.

The beneficial effects of the implementation of the invention are as follows:

1. the nano conductive particles are filled in the polymer matrix in a stretching state to prepare the conductive nano material/polymer composite gas sensor, and the polymer matrix in the stretching state is rapidly swelled by composite steam, so that gaps among conductive particle particles are enlarged, a conductive network formed among the conductive particles is rapidly disconnected, the purpose of rapid response is achieved, and the sensitivity of the sensor is improved.

2. The dispersion liquid a containing the nano conductive particle particles and the solution b containing the polymer particles are mixed according to the proportion, so that the nano conductive particle particles are filled in the polymer, the uniformity of the nano conductive particle particles dispersed in the polymer is improved, and the problem that the conductive network cannot be rapidly disconnected even after the polymer is swelled due to the excessive density among the nano conductive particle particles is solved, and the response speed of the conductive nano material/polymer composite gas sensor is further influenced.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only one embodiment of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a schematic diagram of a conductive nanomaterial/polymer nanocomposite gas sensor in a stretched state according to the present invention;

FIG. 2 is a schematic diagram of a conductive nanomaterial/polymer nano gas sensor in a VOC intra-molecular swollen state according to the present invention;

FIG. 3 is a typical sensitivity characteristic curve of a gas sensor based on the carbon nanotube/polystyrene gas sensor with 10% mass fraction prepared by the present invention under standard test conditions;

FIG. 4 is a characteristic curve of the influence of temperature on sensitivity measured under standard test conditions for a gas sensor based on 10% carbon nanotube/polystyrene gas sensor prepared by the present invention;

FIG. 5 is a characteristic curve of a gas sensor containing 10% mass fraction of carbon nanotubes/polystyrene, which is influenced by temperature and humidity;

FIG. 6 shows representative repeatability data of a gas sensor containing 10% mass fraction of carbon nanotubes/polystyrene prepared according to the present invention under standard test conditions for measuring p-toluene;

FIG. 7 is a graph showing the long term stability data of a typical resistance measured in a real environment based on a gas sensor containing 10% mass fraction of carbon nanotubes/polystyrene prepared according to the present invention;

in the above drawings, the reference numerals denote:

1-a substrate; 2-an electrode; 3-conductive particles; 4-a polymer; 5-VOC molecules.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.